In certain circumstances it is desirable to remove sections of tubular tissue structure from a patient's body. Such tissue may be used in another part of the patient's body, may be transplanted into a second patient's body or may be discarded. As used herein, the term "tubular tissue structure" includes blood vessels, tendons, bile ducts and any other similar tissue formation which is generally tubular in structure and capable of being separated from surrounding tissue. Although the invention herein will be discussed in terms of harvesting blood vessels it should be understood that the apparatus and method described are equally applicable to harvesting other tubular tissue structure.
Vein harvesting is commonly done in connection with coronary artery bypass surgery. The saphenous vein is a subcutaneous vein which is often used for coronary artery bypass grafting, infra-inguinal bypass grafting and vein-vein bypass grafting. Other veins may also be used including the mammary vessel and the lessor saphenous vein. Previously, it has been necessary to make an incision along the full length of the vein section to be removed. The vein is then freed by severing and ligating the branches of the vein, after which the section of the vein can be removed from the patient. The full length incision must then be closed, for example by suturing or stapling. Obviously, the harvesting of the vein in this manner leaves disfiguring scars which are cosmetically undesirable. Additionally, the large incision creates a risk of infection to the patient and may not heal properly, especially with those patient's who have poor circulation in their extremities. Such an incision may create a chronic wound which will not heal.
Devices for harvesting a section of a blood vessel without creating a full length incision have been suggested. U.S. Pat. No. 4,793,346 to Mindich discloses a device for harvesting a section of a blood vessel by making only small incisions at opposite ends of the blood vessel section. The device includes a guide rod which fits inside of the vein section and a tube having an inner diameter slightly larger than the outer diameter of the vein section to be harvested. The tube has one or more knife blades at the leading edge which are connected to an electrical supply. The vein section is removed by making the incision sufficiently deep so as to expose the ends of the blood vessel to be harvested. The blood vessel is cut to expose one end, the guide rod is inserted inside the blood vessel section, and the tube is placed over the end of the blood vessel section to be removed. The tube is then pushed along the blood vessel (into the patient) while rotating the tube to sever the branches of the blood vessel with the knife blade mounted at the leading edge of the tube. Electrical current is supplied to the knife blades to heat the blades and thereby cauterize the ends of the severed branches of the blood vessel. The procedure is continued until the tube has reached the second of the two incisions. The blood vessel is exposed and cut from the patient at the second incision. The tube is then removed from the patient with the blood vessel section inside of the tube. The blood vessel section is then removed from the tube for further treatment and use as desired.
UK patent application GB 20 82 459A discloses a device for harvesting a section of a blood vessel similar to that disclosed in the Mindich patent. Again, two incisions are made, one at each end of the blood vessel section to be harvested. A guide rod is inserted into the blood vessel section through one of the incisions and a tube having a cutting element having a cutting tool at its operative end is passed over the blood vessel section and guide rod assembly. The tube is rotated as it passes over the blood vessel section to sever the connecting branches. After the tube has passed the entire length of the blood vessel section, the section is cut away through the second incision and the tube is removed from the patient with the harvested section inside the tube.
Blood vessel harvesting devices of this type have certain distinct disadvantages. While they eliminate the need for a full length incision to remove the blood vessel segment, two incisions, one at each end of the segment to be harvested, are required in order to remove the blood vessel segment. For patients likely to develop chronic wounds, each additional incision increases the risk to the patient, and it is desirable to keep such incisions as close to the patient's trunk as possible and to minimize the number and size of such incisions. Additionally, such devices are unable to adequately close off several branches of the blood vessel and thus are unable to adequately control bleeding. As a result, the patient suffers greater blood loss than is necessary. These prior devices may also remove more tissue than is necessary because the size of the cutting device is not readily adaptable to the changes in the size of the blood vessel.
In U.S. Pat. No. 5,373,840 to Knighton an improved device and method for vein removal is disclosed which solves some of the problems associated with the use of prior art devices. Knighton discloses an endoscope having a lumen extending longitudinally through the scope body. The endoscope includes means for viewing an area adjacent the distal end of the lumen. The lumen has a lateral dimension large enough to accommodate the blood vessel being harvested and at least one tool for use in harvesting the blood vessel. A first end of the blood vessel section to be harvested is exposed through an incision in the patient's body. A dissecting tool and a gripping tool are inserted through the lumen of the endoscope and used to dissect the blood vessel away from the surrounding connective tissue of the patient's body. Additional tools are provided for use through the lumen of the endoscope to remove body fluids and coagulate bleeding tissue, to ligate and sever side branches from the blood vessel to be harvested, and to ligate and sever a distal end of the blood vessel to be harvested when a desired length of blood vessel has been dissected. Only a small incision in the patient's body is necessary to harvest a relatively long length of blood vessel in a precise and controlled manner using this device and procedure.
Although the '840 patent to Knighton constitutes a significant improvement in devices and techniques for vein harvesting, its multiple tools require more than one operator to complete the procedure. Additionally, its single lumen design requires that the vein be contained within the same lumen as the various tools which are used during the dissection procedure. This makes it possible for the vessel to be damaged during the dissection process by the tools which share the same lumen. It is critical that the segment of blood vessel being harvested is handled with great care since it is destined for reuse (as in arterial bypass). Therefore, it is desirable to isolate the vessel as much as possible from the tools which are used in the dissection.
There is a need for a device and method for vein removal which allows a vein to be harvested in an efficient and safe manner from the body of the patient. Specifically, it would be desirable to provide a device which can be effectively operated by a single operator/physician while at the same time protecting the segment of the vessel being removed from the tools which are used in the procedure.